Firing mechanism with burst control



Oct. 13, 1964 R. H. COLBY 3,152,513

FIRING MECHANISM WITH BURST CONTROL Filed Aug. 13, 1963 4 Sheets-Sheet 1 Fig.1-,

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FIRING MECHANISM WITH BURST CONTROL Filed Aug. 13, 1963 4 Sheets-Sheet 4 INVENTOR. Richmcr HD111 United States Patent FIRING MECHANISM WITH BURST CONTROL Richard Colby, South Hadley, Mass, assignor to. the

United States of America as. represented by the Secrertary of the Army Filed Aug. 113, 1963, Ser. No. 301,924 3 Claims. (Cl. 89-140) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to firearms and more particularly to the firing mechanisms thereof.

It is the object of this invention to provide for firearms a firing mechanism which is easily selected for semiautomatic fire with one round being fired each time the trigger is vpulled, a burst of a predetermined number of rounds each time the trigger is pulled and for full automatic fire, to increase the military value and scope of the firearm, with the firing mechanism being rugged in construction, simple in design and positive (in operation.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a fragmentary elevational view of a firearm at the firing mechanism housing with the right wall of the housing broken away;

FIG. 2 is a section taken along line 2-2 of FIG. 1 and shows the firing mechanism selected for burst fining;

FIG. 3 is a section taken along line 33 of FIG. 2 and shows the actuator raised to the elevated position and the sear actuated to the release position;

FIG. 4 is a section taken along line 44 of FIG. 1;

FIG. 5 is a view similar to FIG. 2 but shows the firing mechanism selected for semiautomatic fire;

FIG. 6 is a view similar to FIGS. 2 and 5 but shows the firing mechanism selected for automatic fire;

FIG. 7 is a view similar to FIG. 3 but shows the sear in the operating rod engaging position;

FIG. 8 is a view similar to FIGS. 3 and 7 but shows the sear lifted by the trigger to release the operating rod;

FIG. 9 is a view similar to FIG. 7 but shows the lifter band actuated by the counter to release the sear to the engaging position; and

FIG. 10 is an exploded perspective view of the firing mechanism.

Shown in the figures is a firearm 12 having a barrel 14, an operating rod 16 which is integral with a bolt (not shown) arranged for reciprocation between a battery and a recoil position, and a firing mechanism 18.

Firing mechanism 18 includes a housing 20 which encircles barrel 14 and operating rod 16. A sear 22 is pivotally mounted in housing 20 above operating rod 16 on a laterally disposed pin 24 so as to extend downwardly and rearwardly therefrom for engagement with a notch 26 in the operating rod to releasably hold the bolt (not shown) in the recoil position. A spring 28 biases sear 22 into engagement with notch 26.

Sear 22 is connected to a lifter 30 which includes a plate 32 slidingly mounted for vertical displacement by T-slot means in the left side of housing 20, a rod 31 which extends laterally from the plate through an accommodating hole 33 in the sear, and a bar 35 which extends laterally from the plate under barrel 14.

Lifter 30 is actuated to disengage sear 22 from notch 26 by a trigger mechanism which includes a trigger bar 34, a trigger 36, a selector 38, a counter 40, and a lifter pawl 42. Trigger bar 34 includes a support section 44, which is pivotal in a lateral plane about a stud 46, and

a beam 48, which is hingedly mounted to the rear end of the support section at 50 for pivotal displacement relative thereto in a vertical plane. Beam 48 is positioned over trigger 36 so as to be raised thereby when pulled to a firing position. A spring 52 biases beam 48 downwardly into contact with trigger 36. Lifter pawl 42 is mounted on the rear end of beam 48 by means of a pin 54 for pivotal displacement between a rearward contacting position, respective to bar 35, and a forward release position clear thereof. A spring 56 biases lifter pawl 42 to the contacting position and an arm 58 extends downwardly and forwardly from lifter pawl 42 for cooperation with counter 40 to actuate the lifter pawl to the release position clear of bar 35 as described hereinafter.

Thus, when trigger 36 is pulled to the firing position, beam 48 is pivoted upwardly so that lifter pawl 42 is raised against lifter 36 which is displaced thereby to actuate sear 22 for release of operating rod 16. With trigger 36 still pulled, sear 22 is releasable from lifter 30, so as to be free to return to the engaging position, by counter 40 through the actuation thereof against arm 58 as hereinafter described.

Counter 40 includes a transversely disposed shaft 60 having a drive wheel 62 mounted on the right end and a counting wheel 64 mounted on the left end. Drive wheel 62 is provided with six rods 65 which are spaced 60 apart and which extend laterally therefrom and such rods comprise two stakes 66 spaced 80 apart and four posts 68 which are shorter than the stakes. Counting wheel 64 is provided with six laterally extending pins 70 also disposed 60 apart. Counter 40 is rotated 60 responsive to each operating cycle of firearm 12 by an actuator 72 which is mounted for vertical displacement in an accommodating T-slot in. the left side of housing 20. A dog 74 is pivotally mounted on the bottom end of actuator 72 for displacement thereby against successive ones of the pins 70. Actuator 72 is vertically displaced responsive to cyclic reciprocation of operating rod 16 through the cooperation of a follower 76 extending from the top of the actuator with a cam groove 78 in the operating rod.

Selection for semiautomatic firing, burst firing and full automatic firing is made by selector 38 which includes a manually rotated knob 80 and a shaft 82 which extends axially therefrom through the bottom of housing 20. A pin 84 is eccentrically mounted in the top end of shaft 82 for vertical extension therefrom through a longitudinal slot 86 in the front end of support section 44 of trigger bar 34 so that rotation of the selector is converted to pivotal displacement of the trigger bar.

Thus, when knob 86 is turned to where pin 84 pivots trigger bar 34 to the position shown in FIG. 5 wherein arm 58 is successively contactable by each .of the rods 65, firearm 12 is selected for semiautomatic fire because, each time the firearm is fired and counter 40 is rotated one pitch, one of such rods is actuated against the arm for pivoting lifter pawl 42 clear of lifter 30 to release sear 22 to the operating rod engaging position for automatically stopping further fire if trigger 36 has not been previously released.

When knob 80 is turned to the position shown in FIG. 2 wherein arm 58 is displaced sufficiently to the left so that it is not contactable by posts 68 but is contactable by stakes 66, firearm 12 is selected for firing bursts of three rounds because, when trigger 36 is held in firing position, three rounds will be fired before one of the stakes contacts the arm to stop the firing.

When knob 80 is turned still further to the right to the position shown in FIG. 6 wherein arm 58 is clear of contact by stakes 66 or posts 68, firearm 12 is selected for automatic fire because firing is controlled solely by trigger 36 and will continue as long as the trigger is pulled to the firing position and ammunition is available.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a firearm having an operating rod disposed for reciprocation responsive to cyclic firing of the firearm, a sear pivotal between an engaging position respective to the operating rod to stop firing of the firearm and a release position clear of the operating rod, a spring for biasing said sear to the engaging position, a lifter connected to said sear for displacement therewith, a trigger pivotal to a firing position, a trigger bar including a beam disposed for pivotal displacement in a vertical plane of the firearm by said trigger when pivoted to the firing position, a pawl pivotally mounted on said beam for releasable contact with said lifter to transmit displacement of said trigger to the firing position to said sear for displacement thereof to the release position, a selector disposed for pivotally displacing said trigger bar in a lateral plane of the firearm to preselected positions, an actuator disposed for cyclic displacement by the operating rod, and a counter operationally disposed between said actuator and said pawl for eifecting semiautomatic fire, burst firing of a predetermined number of rounds each time said trigger is pivoted to the firing position and automatic fire according to the position to which said trigger bar is pivoted by said selector.

2. The firing mechanism as defined in claim 1 wherein said counter includes means disposed in cooperation with said actuator for translating reciprocation of the operating rod to rotation of said counter, and a plurality of rods of different preselected lengths and predetermined interrelationship mounted on said counter for selective contact with said pawl according to the position to which said trigger bar is pivoted by said selector for disengaging said pawl from said lifter to release said sear to the engaging position.

3. The firing mechanism as defined in claim 1 wherein said counter is provided with a shaft, a drive wheel mounted on one end of said shaft and a counting Wheel mounted on the opposite end, a plurality of pins extending symmetrically from the side of said driving wheel for successive contact by said actuator for converting reciprocation of said operating rod to rotation of said counter, a plurality of stakes and a plurality of posts totaling the number of said pins symmetrically mounted on said counting wheel so as to extend therefrom and with said stakes extending outwardly farther than said posts, and wherein said pawl is arranged for contact by each of said stakes and posts for actuation thereby clear of said lifter after each firing cycle of the firearm when said trigger bar is pivoted by said selector to one of the preselected positions, is contactable only by said stakes to release said sear after a predetermined number of firing cycles when said trigger bar is pivoted to another of the preselected positions, and is clear of contact by said posts and said stakes so that said sear is controllable only by said trigger when the trigger bar is pivoted to still another one of the preselected positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,548,622 Sampson et al Apr. 10, 1951 

1. IN A FIREARM HAVING AN OPERATING ROD DISPOSED FOR RECIPROCATION RESPONSIVE TO CYCLIC FIRING OF THE FIREARM, A SEAR PIVOTAL BETWEEN AN ENGAGING POSITION RESPECTIVE TO THE OPERATING ROD TO STOP FIRING OF THE FIREARM AND A RELEASE POSITION CLEAR OF THE OPERATING ROD, A SPRING FOR BIASING SAID SEAR TO THE ENGAGING POSITION, A LIFTER CONNECTED TO SAID SEAR FOR DISPLACEMENT THEREWITH, A TRIGGER PIVOTAL TO A FIRING POSITION, A TRIGGER BAR INCLUDING A BEAM DISPOSED FOR PIVOTAL DISPLACEMENT IN A VERTICAL PLANE OF THE FIREARM BY SAID TRIGGER WHEN PIVOTED TO THE FIRING POSITION, A PAWL PIVOTALLY MOUNTED ON SAID BEAM FOR RELEASABLE CONTACT WITH SAID LIFTER TO TRANSMIT DISPLACEMENT OF SAID TRIGGER TO THE FIRING POSITION TO SAID SEAR FOR DISPLACEMENT THEREOF TO THE RELEASE POSITION, A SELECTOR DISPOSED FOR PIVOTALLY DISPLACING SAID TRIGGER BAR IN A LATERAL PLANE OF THE FIREARM TO PRESELECTED POSITIONS, AN ACTUATOR DISPOSED FOR CYCLIC DISPLACEMENT BY THE OPERATING ROD, AND A COUNTER OPERATIONALLY DISPOSED BETWEEN SAID ACTUATOR AND SAID PAWL FOR EFFECTING SEMIAUTOMATIC FIRE, BURST FIRING OF A PREDETERMINED NUMBER OF ROUNDS EACH TIME SAID TRIGGER IS PIVOTED TO THE FIRING POSITION AND AUTOMATIC FIRE ACCORDING TO THE POSITION TO WHICH SAID TRIGGER BAR IS PIVOTED BY SAID SELECTOR. 